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Metals/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim bends a spoon trying to scoop out ice cream from a container. Moby walks over to him and gives him a letter. MOBY: Beep. Tim reads from a typed letter. TIM: Dear Tim and Moby, what is metal and why do we need it? Thank you, SideNote3540. You use things made of metal every day: cars, jewelry, silverware, shoes, belts, dishwashers, school bells, lightbulbs, pens, cellphones, and mailboxes, just to name a few. Images of these objects appear on screen. Moby taps himself. MOBY: Beep. TIM: Oh, yeah. Robots are made of metal too. But, just what a metal is, is kind of hard to define. A chemist might tell you that metals are elements with metallic qualities. MOBY: Beep. TIM: Well, that's not as silly as it sounds. An image shows "The Periodic Table of Elements." Elements are color coordinated by type. Metal elements are then shown in red. TIM: See, on the Periodic Table, every element falls into one of three categories: metals, nonmetals, and metalloids. Metals are the most common type, and they’re defined by certain physical and chemical properties. Images and animations show the qualities of metals with luster as a texture; conductors as moving dots; a solid as a cube; malleable as a curved metal; ductile as a wire; hardness as resistant to scratching coils; and elasticity as one curved and two straight pieces of metals. TIM: In terms of their physical properties, metals have luster, or shininess; are good conductors of heat and electricity; are solid at room temperature, oh, except for mercury; are malleable, or able to be hammered or bent into shape; are ductile, so that they can be stretched into wires or other shapes without breaking; have hardness, or resistance to scraping and abrasion; and have elasticity, the ability to go back to their original shape. MOBY: Beep. TIM: Well, most metals have most of these qualities. Moby frowns and looks out of the corner of his eyes at Tim. TIM: Well, hey, I'm doing my best. We can narrow down what metals are by looking at their chemical properties. An animation shows the positive valences of atoms "Na" and "Cl." Rings and dots representing electrons are around the letters. One of Na's dots moves over to Cl's rings and Na turns into Na+. TIM: First, they have positive valences, which means they give electrons to the atoms they bond with. Because metals give up negative electrons so easily, they tend to form cations, positively charged atoms. An amination shows a building, bicycle, and fork rusting. TIM: Also, metals oxidize, corroding when they’re exposed to dampness. MOBY: Beep. TIM: No, you can't usually just go outside and pick metal up off the ground. An image shows gold flakes on the ground and the veins and ores in mineral deposits also on the ground. An industrial plant's crane digs metal out of a hole in the ground. TIM: Only native metals like copper, gold, platinum, and silver are found by themselves, and even then they're usually buried in the ground. Most metals are found in veins mixed together with ores, masses of mineral that carry a lot of metal. The veins are mined for the ore. Removing impurities from the ore so that only the metal remains is called refining. MOBY: Beep. TIM: Well, after metal is refined, it's often mixed with nonmetals or other metals to form alloys. Alloys have properties that make them more useful than pure metals. An image shows a cannon, bell, coins, medal and wall plaque, all made of bronze. TIM: Bronze, an alloy of copper and tin, is harder and more resistant to corrosion than either copper or tin by themselves. An image shows steel's surface. TIM: Steel is an alloy of iron and other elements, especially carbon. Images show a knife, welding tool, car and airplane, and knight's armor. TIM: Since carbon adds hardness, steel has a lot of industrial uses including cutting tools, welding, car and airplane parts, and armor. Tim holds the spoon he bent scooping ice cream. Moby looks at it. TIM: Eating utensils are often made of stainless steel, which is strong and rustproof. MOBY: Beep. TIM: Yeah, I don't know what this one's made of. Hmmm. Category:BrainPOP Transcripts